From patchwork Tue Feb 26 12:06:09 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 10830065 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3034A17EF for ; Tue, 26 Feb 2019 12:06:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1D57D2B079 for ; Tue, 26 Feb 2019 12:06:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 112E12B24A; Tue, 26 Feb 2019 12:06:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BA86F2B2EE for ; Tue, 26 Feb 2019 12:06:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726567AbfBZMGT (ORCPT ); Tue, 26 Feb 2019 07:06:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:45458 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725935AbfBZMGT (ORCPT ); Tue, 26 Feb 2019 07:06:19 -0500 Received: from localhost.localdomain (bl8-197-74.dsl.telepac.pt [85.241.197.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 79B3C217F9; Tue, 26 Feb 2019 12:06:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551182778; bh=jgKi5ePaQkVJZHJjY1giBwluAmfoWWtTBzNZhFv+QLU=; h=From:To:Cc:Subject:Date:From; b=L9ll3GDvj/R+eNUVQxBYw4TgeZxu/PzbjXPnK8BFD/v5QRCAIBeoy7uf16PeVEcN2 zCfnWQ/jEkP+SSGFZNP4v3LU/RkwmQFzeMhkiFq1+Sl0SV4aTFcw5PC0vAYkPE1Cw+ JBDMRW4fGYP+RDiwD5UtqvXssiv5wcJU0TDfmDPU= From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Cc: ce3g8jdj@umail.furryterror.org Subject: [PATCH] Btrfs: fix deadlock between clone/dedupe and rename Date: Tue, 26 Feb 2019 12:06:09 +0000 Message-Id: <20190226120609.14450-1-fdmanana@kernel.org> X-Mailer: git-send-email 2.11.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Filipe Manana Reflinking (clone/dedupe) and rename are operations that operate on two inodes and therefore need to lock them in the same order to avoid ABBA deadlocks. It happens that Btrfs' reflink implementation always locked them in a different order from VFS's lock_two_nondirectories() helper, which is used by the rename code in VFS, resulting in ABBA type deadlocks. Btrfs' locking order: static void btrfs_double_inode_lock(struct inode *inode1, struct inode *inode2) { if (inode1 < inode2) swap(inode1, inode2); inode_lock_nested(inode1, I_MUTEX_PARENT); inode_lock_nested(inode2, I_MUTEX_CHILD); } VFS's locking order: void lock_two_nondirectories(struct inode *inode1, struct inode *inode2) { if (inode1 > inode2) swap(inode1, inode2); if (inode1 && !S_ISDIR(inode1->i_mode)) inode_lock(inode1); if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1) inode_lock_nested(inode2, I_MUTEX_NONDIR2); } Fix this by killing the btrfs helper function that does the double inode locking and replace it with VFS's helper lock_two_nondirectories(). Reported-by: Zygo Blaxell Fixes: 416161db9b63e3 ("btrfs: offline dedupe") Signed-off-by: Filipe Manana Reviewed-by: David Sterba --- fs/btrfs/ioctl.c | 21 +++------------------ 1 file changed, 3 insertions(+), 18 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 9c8e1734429c..6e1119496721 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3206,21 +3206,6 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info, return ret; } -static void btrfs_double_inode_unlock(struct inode *inode1, struct inode *inode2) -{ - inode_unlock(inode1); - inode_unlock(inode2); -} - -static void btrfs_double_inode_lock(struct inode *inode1, struct inode *inode2) -{ - if (inode1 < inode2) - swap(inode1, inode2); - - inode_lock_nested(inode1, I_MUTEX_PARENT); - inode_lock_nested(inode2, I_MUTEX_CHILD); -} - static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1, struct inode *inode2, u64 loff2, u64 len) { @@ -3989,7 +3974,7 @@ static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in, if (same_inode) inode_lock(inode_in); else - btrfs_double_inode_lock(inode_in, inode_out); + lock_two_nondirectories(inode_in, inode_out); /* * Now that the inodes are locked, we need to start writeback ourselves @@ -4039,7 +4024,7 @@ static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in, if (same_inode) inode_unlock(inode_in); else - btrfs_double_inode_unlock(inode_in, inode_out); + unlock_two_nondirectories(inode_in, inode_out); return ret; } @@ -4069,7 +4054,7 @@ loff_t btrfs_remap_file_range(struct file *src_file, loff_t off, if (same_inode) inode_unlock(src_inode); else - btrfs_double_inode_unlock(src_inode, dst_inode); + unlock_two_nondirectories(src_inode, dst_inode); return ret < 0 ? ret : len; }